Seepage Forests

Seepage forests are forested wetlands typically found in dissected or undulating landscapes
on side slopes, stream-head swales, ravine bottoms, or around springs on hillslopes.
They have saturated soil but standing water is generally absent. These woody wetlands are fed by subsurface or groundwater seepage and occur usually
on low slopes where groundwater reaches an impervious restrictive layer and seeps
laterally from hill slopes.There may be small rivulets arising from springs that surface in the seepage forest
and these may coalesce downslope into first-order outlet streams. Seepage forests
may be gravelly or peaty and may be calcareous, circumneutral, or acidic. They often
have distintive microtopographic features with numerous hummocks. A few inches in
elevation gain can mean the difference between sites that support typical upland species
and those that support obligate wetland species. Most modern seepage forests are relatively
thickly vegetated and often contain subcanopy and shrub layers. Ferns, herbs, and
sedges are often abundant in the herb layer. Bryophyte mats are common as well. Seepage
forests with alkaline groundwaters are classified by some as forested fens. Many seepage
slope "forests" are dominated by species that are benefitted by fire and prefer open
sunlit conditions. It is quite likely that most of the modern seepage "forests" would
have had a more open woodland physiognomy during presettlement times. Most are embedded
in otherwise dry to xeric oak or oak-pine dominated forests and woodlands that are
fire-adapted. Fires would have likely moved from these adjacent dry woodlands into
and across the relatively narrow seepage communities. Exceptions to this however include
high-elevation seepage forest communities in the Blue Ridge Mountains between 2,500
and 5,000 ft elevation that are associated with mesic cove-hardwood or northern-hardwood
forests. In such examples fire has likely not played a significant role.